There's more to the platform wars than mobile - Android is starting to take off in non-mobile markets in a massive way - Internet of Things, Television (Chromecast), etc. To date Linux has been the dominant OS but Android is now taking some embedded designs which would have run Linux. The effective decoupling of Android from carriers for non-mobile markets + the richness of tools and the existing developer ecosystem will likely cement Android as the definitive open source OS of the next decade. This will have pluses for Google but also unintended consequences.

A common misconception among people who don't really understand what Linux is - one that I'm seeing pop up more and more now that people are trying to paint Android in a negative light - i.e., as competition to not just iOS, but also the noble and open source Linux.

Repeat after me: Android is just as much 'Linux' as Ubuntu, Debian, Red Hat, or anything else that uses the Linux kernel. Technically, a better term would be 'Linux distribution', since Linux in and of itself is just a kernel. Wikipedia defines 'Linux distribution' quite well:

A Linux distribution (often called distro for short) is a member of the family of Unix-like operating systems built on top of the Linux kernel. Such distributions are operating systems including a large collection of software applications such as word processors, spreadsheets, media players, and database applications. These operating systems consist of the Linux kernel and, usually, a set of libraries and utilities from the GNU Project, with graphics support from the X Window System. Distributions optimized for size may not contain X and tend to use more compact alternatives to the GNU utilities, such as BusyBox, uClibc, or dietlibc.

Android is a Linux distribution, and is an addition to the Linux ecosystem - not a challenger. Painting it as such is just a sign of ignorance.

Actually, no, saying that Android is not Linux is not at all like saying that a Rolls Royce is not a car.

Unless you are going to make up a new definition of the word "Linux" then it refers to one of two things (I think two things are already enough).

The first thing that "Linux" can mean is the kernel (you can argue that technically this is the only meaning). In that context an operating system is more than its kernel. Saying that Android is Linux would be like saying that a car is an engine. Obviously a car is not an engine, though a working car will contain an engine. So in this sense Android is not Linux.

The second thing that "Linux" can refer to is the operating system that has been popularized under the term "Linux." Android is a different operating system than the operating system known as Linux, so in this sense also Android is not Linux. To continue with the analogy, if you take a Jeep and put a Ford engine or a Chevrolet engine in it (both of which I have seen done), it doesn't turn the Jeep into a Ford or a Chevy.